Amazon introduced its Kindle Paperwhite e-reader today, showcasing the new device's lighted screen and lengthy battery life at an event in Santa Monica, Calif.

With more contrast and brightness than found on previous Kindles, the Paperwhite has a resolution of 212 pixels per inch (62 percent higher resolution than the current Kindle) and boasts eight weeks of battery life with the light on at half brightness (based on 30 minutes of use a day with WiFi off) -- twice as much longevity as the Nook Glowlight, CEO Jeff Bezos said at the event. The Kindle Paperwhite is 9.1mm thick, and weighs 7.5 ounces. It's "thinner than a magazine and lighter than a paperback," Bezos said.

The device will cost $119 and ships October 1. A 3G version will be available for $179. A $69 entry-level Kindle, $10 cheaper than the previous edition, will be available September 14.

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The light guide on the device represents four years of research and development work at Amazon, according to Bezos, who said that Paperwhite has 25 percent more contrast than the current Kindles.

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The Paperwhite offers a capacitive touch screen rather than the IR-based touch screen found on competing touch-screen models from Barnes & Noble, Sony, and Kobo. The technology dates back to Amazon's 2009 acquisition of a multitouch hardware company called Touchco, which got tasked with developing a capacitive touch screen for Amazon's e-ink e-readers.

The software includes a feature that calculates how much time, not just pages, is needed to finish the book based on a reader's individual habits.